Soluble Receptor for Advanced Glycation End Products Alleviates Nephritis in (NZB/NZW)F1 Mice

The role of O-GlcNAcylation in bone metabolic diseases

O-GlcNAcylation, as a post-translational modification, can modulate cellular activities such as kinase activity, transcription-translation, protein degradation, and insulin signaling by affecting the function of the protein substrate, including cellular localization of proteins, protein stability, and protein/protein interactions. Accumulating evidence suggests that dysregulation of O-GlcNAcylation is associated with disease progression such as cancer, neurodegeneration, and diabetes. Recent studies suggest that O-GlcNAcylation is also involved in the regulation of osteoblast, osteoclast and chondrocyte differentiation, which is closely related to the initiation and development of bone metabolic diseases such as osteoporosis, arthritis and osteosarcoma. However, the potential mechanisms by which O-GlcNAcylation regulates bone metabolism are not fully understood. In this paper, the literature related to the regulation of bone metabolism by O-GlcNAcylation was summarized to provide new potential therapeutic strategies for the treatment of orthopedic diseases such as arthritis and osteoporosis.

Soluble receptors for advanced glycation end-products prevent unilateral ureteral obstruction-induced renal fibrosis

Introduction: The receptor for advanced glycation end products (RAGE) and its ligands, such as high-mobility group protein box 1 (HMGB1), play an important role in the accumulation of extracellular matrix in chronic kidney diseases with tubulointerstitial fibrosis. Blocking RAGE signaling with soluble RAGE (sRAGE) is a therapeutic candidate for renal fibrosis. Methods: NRK-52E cells were stimulated with or without HMGB1 and incubated with sRAGE in vitro. Sprague-Dawley rats were intraperitoneally treated with sRAGE after unilateral ureteral obstruction (UUO) operation in vivo. Results: HMBG1-stimulated NRK-52E cells showed increased fibronectin expression, type I collagen, α-smooth muscle actin, and connective tissue growth factor, which were attenuated by sRAGE. The mitogen-activated protein kinase (MAPK) pathway and nuclear translocation of nuclear factor kappa B (NF-κB) were enhanced in NRK-52E cells exposed to HMBG1, and sRAGE treatment alleviated the activation of the MAPK and NF-κB pathways. In the UUO rat models, sRAGE significantly ameliorated the increased renal fibronectin, type I collagen, and α-smooth muscle actin expressions. Masson's trichrome staining confirmed the anti-fibrotic effect of sRAGE in the UUO rat model. RAGE also significantly attenuated the activation of the MAPK pathway and NF-κB, as well as the increased number of infiltrated macrophages within the tubulointerstitium in the kidney of the UUO rat models. Conclusion: These findings suggest that RAGE plays a pivotal role in the pathogenesis of renal fibrosis and that its inhibition by sRAGE may be a potential therapeutic approach for renal fibrosis.

Amelioration of nephritis in receptor for advanced glycation end-products (RAGE)-deficient lupus-prone mice through neutrophil extracellular traps

The receptor for advanced glycation end-products (RAGE) is a pattern recognition receptor that regulates inflammation, cell migration, and cell fate. Systemic lupus erythematosus (SLE) is a chronic multiorgan autoimmune disease. To understand the function of RAGE in SLE, we generated RAGE-deficient (Ager-/-) lupus-prone mice by backcrossing MRL/MpJ-Faslpr/J (MRL-lpr) mice with Ager-/- C57BL/6 mice. In 18-week-old Ager-/- MRL-lpr, the weights of the spleen and lymph nodes, as well as the frequency of CD3+CD4-CD8- cells, were significantly decreased. Ager-/- MRL-lpr mice had significantly reduced urine albumin/creatinine ratios and markedly improved renal pathological scores. Moreover, neutrophil infiltration and neutrophil extracellular trap formation in the glomerulus were significantly reduced in Ager-/- MRL-lpr. Our study is the first to reveal that RAGE can have a pathologic role in immune cells, particularly neutrophils and T cells, in inflammatory tissues and suggests that the inhibition of RAGE may be a potential therapeutic strategy for SLE.

Urinary excretion of amino acids and their advanced glycation end-products (AGEs) in adult kidney transplant recipients with emphasis on lysine: furosine excretion is associated with cardiovascular and all-cause mortality

Arginine (Arg) and lysine (Lys) moieties of proteins undergo various post-translational modifications (PTM) including enzymatic N^G- and N^ε-methylation and non-enzymatic N^G- and N^ε-glycation. In a large cohort of stable kidney transplant recipients (KTR, n = 686), high plasma and low urinary concentrations of asymmetric dimethylarginine (ADMA), an abundant PTM metabolite of Arg, were associated with cardiovascular and all-cause mortality. Thus, the prediction of the same biomarker regarding mortality may depend on the biological sample. In another large cohort of stable KTR (n = 555), higher plasma concentrations of N^ε-carboxymethyl-lysine (CML) and N^ε-carboxyethyl-lysine (CEL), two advanced glycation end-products (AGEs) of Lys, were associated with higher cardiovascular mortality. Yet, the associations of urinary AGEs with mortality are unknown. In the present study, we measured 24 h urinary excretion of Lys, CML, and furosine in 630 KTR and 41 healthy kidney donors before and after donation. Our result indicate that lower urinary CML and lower furosine excretion rates are associated with higher mortality in KTR, thus resembling the associations of ADMA. Lower furosine excretion rates were also associated with higher cardiovascular mortality. The 24 h urinary excretion rate of amino acids and their metabolites decreased post-donation (varying as little as − 24% for CEL, and as much as − 62% for ADMA). For most amino acids, the excretion rate was lower in KTR than in donors pre-donation [except for S-(1-carboxyethyl)-l-cysteine (CEC) and N^G-carboxyethylarginine (CEA)]. Simultaneous GC–MS measurement of free amino acids, their PTM metabolites and AGEs in urine is a non-invasive approach in kidney transplantation.

Cellular Response against Oxidative Stress, a Novel Insight into Lupus Nephritis Pathogenesis

The interaction of reactive oxygen species (ROS) with lipids, proteins, nucleic acids and hydrocarbonates promotes acute and chronic tissue damage, mediates immunomodulation and triggers autoimmunity in systemic lupus erythematous (SLE) patients. The aim of the study was to determine the pathophysiological mechanisms of the oxidative stress-related damage and molecular mechanisms to counteract oxidative stimuli in lupus nephritis. Our study included 38 SLE patients with lupus nephritis (LN group), 44 SLE patients without renal impairment (non-LN group) and 40 healthy volunteers as control group. In the present paper, we evaluated serum lipid peroxidation, DNA oxidation, oxidized proteins, carbohydrate oxidation, and endogenous protective systems. We detected defective DNA repair mechanisms via 8-oxoguanine-DNA-glycosylase (OGG1), the reduced regulatory effect of soluble receptor for advanced glycation end products (sRAGE) in the activation of AGE-RAGE axis, low levels of thiols, disulphide bonds formation and high nitrotyrosination in lupus nephritis. All these data help us to identify more molecular mechanisms to counteract oxidative stress in LN that could permit a more precise assessment of disease prognosis, as well as developing new therapeutic targets.

The Immune Tolerance Role of the HMGB1-RAGE Axis

The disruption of the immune tolerance induces autoimmunity such as systemic lupus erythematosus and vasculitis. A chromatin-binding non-histone protein, high mobility group box 1 (HMGB1), is released from the nucleus to the extracellular milieu in particular environments such as autoimmunity, sepsis and hypoxia. Extracellular HMGB1 engages pattern recognition receptors, including Toll-like receptors (TLRs) and the receptor for advanced glycation endproducts (RAGE). While the HMGB1-RAGE axis drives inflammation in various diseases, recent studies also focus on the anti-inflammatory effects of HMGB1 and RAGE. This review discusses current perspectives on HMGB1 and RAGE’s roles in controlling inflammation and immune tolerance. We also suggest how RAGE heterodimers responding microenvironments functions in immune responses.

The receptor for advanced glycation endproducts (RAGE) modulates T cell signaling

The receptor for advanced glycation endproducts (RAGE) is expressed in T cells after activation with antigen and is constitutively expressed in T cells from patients at-risk for and with type 1 diabetes mellitus (T1D). RAGE expression was associated with an activated T cell phenotype, leading us to examine whether RAGE is involved in T cell signaling. In primary CD4+ and CD8+ T cells from patients with T1D or healthy control subjects, RAGE- cells showed reduced phosphorylation of Erk. To study T cell receptor signaling in RAGE+ or–T cells, we compared signaling in RAGE+/+ Jurkat cells, Jurkat cells with RAGE eliminated by CRISPR/Cas9, or silenced with siRNA. In RAGE KO Jurkat cells, there was reduced phosphorylation of Zap70, Erk and MEK, but not Lck or CD3ξ. RAGE KO cells produced less IL-2 when activated with anti-CD3 +/- anti-CD28. Stimulation with PMA restored signaling and (with ionomycin) IL-2 production. Silencing RAGE with siRNA also decreased signaling. Our studies show that RAGE expression in human T cells is associated with an activated signaling cascade. These findings suggest a link between inflammatory products that are found in patients with diabetes, other autoimmune diseases, and inflammation that may enhance T cell reactivity.

Punicalagin Ameliorates Lupus Nephritis via Inhibition of PAR2

Lupus nephritis (LN) is the most frequent phenotype in patients with systemic lupus erythematosus (SLE) and has a high rate of progression to end-stage renal disease, in spite of intensive treatment and maintenance therapies. Recent evidence suggests that protease-activated receptor-2 (PAR2) is a therapeutic target for glomerulonephritis. In this study, we performed a cell-based high-throughput screening and identified a novel potent PAR2 antagonist, punicalagin (PCG, a major polyphenol enriched in pomegranate), and evaluated the effects of PCG on LN. The effect of PCG on PAR2 inhibition was observed in the human podocyte cell line and its effect on LN was evaluated in NZB/W F1 mice. In the human podocyte cell line, PCG potently inhibited PAR2 (IC₅₀ = 1.5 ± 0.03 µM) and significantly reduced the PAR2-mediated activation of ERK1/2 and NF-κB signaling pathway. In addition, PCG significantly decreased PAR2-induced increases in ICAM-1 and VCAM-1 as well as in IL-8, IFN-γ, and TNF-α expression. Notably, the intraperitoneal administration of PCG significantly alleviated kidney injury and splenomegaly and reduced proteinuria and renal ICAM-1 and VCAM-1 expression in NZB/W F1 mice. Our results suggest that PCG has beneficial effects on LN via inhibition of PAR2, and PCG is a potential therapeutic agent for LN.

Targeting the receptor for advanced glycation end products (RAGE) in type 1 diabetes

Type 1 diabetes (T1D) is one of the most common chronic diseases manifesting in early life, with the prevalence increasing worldwide at a rate of approximately 3% per annum. The prolonged hyperglycaemia characteristic of T1D upregulates the receptor for advanced glycation end products (RAGE) and accelerates the formation of RAGE ligands, including advanced glycation end products, high-mobility group protein B1, S100 calcium-binding proteins, and amyloid-beta. Interestingly, changes in the expression of RAGE and these ligands are evident in patients before the onset of T1D. RAGE signals via various proinflammatory cascades, resulting in the production of reactive oxygen species and cytokines. A large number of proinflammatory ligands that can signal via RAGE have been implicated in several chronic diseases, including T1D. Therefore, it is unsurprising that RAGE has become a potential therapeutic target for the treatment and prevention of disease. In this review, we will explore how RAGE might be targeted to prevent the development of T1D.

Relevance of Receptor for Advanced Glycation end Products (RAGE) in Murine Antibody-Mediated Autoimmune Diseases

It is incompletely understood how self-antigens become targets of humoral immunity in antibody-mediated autoimmune diseases. In this context, alarmins are discussed as an important level of regulation. Alarmins are recognized by various receptors, such as receptor for advanced glycation end products (RAGE). As RAGE is upregulated under inflammatory conditions, strongly binds nucleic acids and mediates pro-inflammatory responses upon alarmin recognition, our aim was to examine its contribution to immune complex-mediated autoimmune diseases. This question was addressed employing RAGE−/− animals in murine models of pristane-induced lupus, collagen-induced, and serum-transfer arthritis. Autoantibodies were assessed by enzyme-linked immunosorbent assay, renal disease by quantification of proteinuria and histology, arthritis by scoring joint inflammation. The associated immune status was determined by flow cytometry. In both disease entities, we detected tendentiously decreased autoantibody levels in RAGE−/− mice, however no differences in clinical outcome. In accordance with autoantibody levels, a subgroup of the RAGE−/− animals showed a decrease in plasma cells, and germinal center B cells and an increase in follicular B cells. Based on our results, we suggest that RAGE deficiency alone does not significantly affect antibody-mediated autoimmunity. RAGE may rather exert its effects along with other receptors linking environmental factors to auto-reactive immune responses.

Erythropoietin Treatment Ameliorates Lupus Nephritis of MRL/lpr Mice

An increasing body of data has shown that erythropoietin (EPO) plays multiple roles in inflammation control and immunoregulation. However, less attention has been given to its effects on lupus nephritis (LN). In this study, we investigated the therapeutic effects of EPO on LN in MRL/lpr mice, a well-studied animal model for lupus. MRL/lpr mice were randomly divided into an EPO and control group. Mice in the EPO group were treated with EPO; saline was given to the control group. Both groups were treated for 10 weeks. We analyzed the differences of general disease condition, histopathologic changes, Th lymphocytes subsets, and the expression of inflammatory factors of mice between the groups. Compared to the control group, mice in the EPO group showed less spleen hyperplasia, less urinary protein, and lower serum anti-dsDNA antibody; they also had lower renal histopathologic scores and less deposition of IgG/C3 within glomeruli. Moreover, Th1 and Th17 levels were decreased, while Th2 and Treg levels were increased in the spleen, and the expression of inflammatory cytokines decreased in both the spleen and kidneys. EPO increased Th2 and Treg lymphocytes, decreased Th1, Th17 lymphocytes in the spleen, and inhibited the inflammatory reactions in both the spleen and kidneys, thus ameliorating LN of MRL/lpr mice.

Intranuclear delivery of the transcription modulation domain of Tbet-improved lupus nephritis in (NZB/NZW) F1 lupus-prone mice

Excessive expression of Tbet and IFNγ is evidence of systemic lupus erythematosus (SLE) in lupus patients. In this study, the nucleus-transducible form of Transcription Modulation Domain (TMD) of Tbet (ntTbet-TMD), which is a fusion protein between Protein Transduction Domain Hph-1 (Hph-1-PTD) and the TMD of Tbet comprising DNA binding domain and isotype-specific domain, was generated to inhibit Tbet-mediated transcription in the interactomic manner. ntTbet-TMD was effectively delivered into the nucleus of the cells and specifically inhibited Tbet-mediated transcription without influencing the differentiation of other T cell subsets and signaling events for T cell activation. The severity of nephritis was significantly reduced by ntTbet-TMD as effectively as methylprednisolone in lupus-prone mice. The number of Th1, Th2 or Th17 cells and the secretion of their cytokines substantially decreased in the spleen and kidney of lupus-prone mice by ntTbet-TMD treatment. In contrast to methylprednisolone, the marked increase of Treg cells and the secretion of their immunosuppressive cytokine were detected in the spleen of (NZB/NZW) F1 mice treated with ntTbet-TMD. Thus, ntTbet-TMD can improve nephritis in lupus-prone mice by modulating the overall proinflammatory microenvironment and rebalancing T cell subsets, leading to new immune therapeutics for Th1-mediated autoimmune diseases.

Renal outcome after kidney-transplantation in Korean patients with lupus nephritis

We investigated renal outcome of kidney-transplantation in 19 Korean recipients with biopsy-proven lupus nephritis and compared it with 18 Korean age- and gender-matched recipients without lupus nephritis who were diagnosed with end-stage renal disease caused by renal diseases other than lupus nephritis in a single centre. We reviewed histological findings of kidneys and calculated cumulative dose of immunosuppressive agents. We assessed renal flare of systemic lupus erythematosus, recurrence of lupus nephritis and graft failure as prognosis. The mean age of recipients with lupus nephritis was 43.5 years and all patients were female. Six patients had class III, 10 had class IV and three had class V. There were no meaningful differences in demographic data, renal replacement modality, cumulative doses of immunosuppressants and prognosis between recipients with and without lupus nephritis. Eight patients experienced renal flare of systemic lupus erythematosus, but there were no cases of recurrence of lupus nephritis or graft failure in recipients with lupus nephritis. Kidney-recipients with class IV lupus nephritis exhibited a lower cumulative renal flare of systemic lupus erythematosus free survival rate than those with class III lupus nephritis. In conclusion, renal outcome of kidney-transplantation in patients with lupus nephritis is similar to that in those without lupus nephritis, and class IV was associated with renal flare of systemic lupus erythematosus.

Autoantibodies to box A of high mobility group box 1 in systemic lupus erythematosus

Autoantibodies to nuclear structures are a hallmark of systemic lupus erythematosus (SLE), including autoantibodies to nuclear protein high mobility group box 1 (HMGB1). HMGB1 consists of three separate domains: box A, box B and an acidic tail. Recombinant box A acts as a competitive antagonist for HMGB1 and might be an interesting treatment option in SLE. However, antibodies to box A might interfere. Therefore, levels of anti-box A were examined in SLE patients in association with disease activity and clinical parameters. Serum anti-box A was measured in 86 SLE patients and 44 age- and sex-matched healthy controls (HC). Serum samples of 28 patients with primary Sjögren's syndrome and 32 patients with rheumatoid arthritis were included as disease controls. Anti-HMGB1 and anti-box B levels were also measured by enzyme-linked immunosorbent assay during quiescent disease [SLE Disease Activity Index (SLEDAI) ≤ 4, n = 47] and active disease (SLEDAI ≥ 5, n = 39). Anti-box A levels in active SLE patients were higher compared to quiescent patients, and were increased significantly compared to HC and disease controls. Anti-box A levels correlated positively with SLEDAI and anti-dsDNA levels and negatively with complement C3 levels. Increased levels of anti-box A antibodies were present in the majority of patients with nephritic (73%) and non-nephritic exacerbations (71%). Antibodies to the box A domain of HMGB1 might be an interesting new biomarker, as these had a high specificity for SLE and were associated with disease activity. Longitudinal studies should be performed to evaluate whether these antibodies perform better in predicting an exacerbation, especially non-nephritic exacerbations.

Blockade of receptor for advanced glycation end products protects against systolic overload-induced heart failure after transverse aortic constriction in mice

Heart failure is the consequence of sustained, abnormal neurohormonal and mechanical stress and remains a leading cause of death worldwide. The aim of this work was to identify whether blockade of receptor for advanced glycation end products (RAGE) protected against systolic overload-induced heart failure and investigate the possible underlying mechanism. It was found that RAGE mRNA and protein expression was up-regulated in cardiac tissues from mice subjected to pressure overload by transverse aortic constriction (TAC). Importantly, inhibition of RAGE by treatment with soluble RAGE (sRAGE) or FPS-ZM1 (a high-affinity RAGE-specific inhibitor) for 8 weeks attenuated cardiac remodeling (including cardiac hypertrophy and fibrosis), and dysfunction in mice exposed to TAC. Furthermore, treatment of TAC mice with sRAGE or FPS-ZM1 enhanced phosphorylation of AMPK and reduced phosphorylation of mTOR and protein expression of NFκB p65 in cardiac tissues. In addition, treatment of TAC mice with sRAGE or FPS-ZM1 abated oxidative stress, attenuated endoplasmic reticulum stress, and suppressed inflammation in cardiac tissues. These data demonstrated the benefits of blocking RAGE on the progression of systolic overload-induced heart failure in mice, which was possibly through modulating AMPK/mTOR and NFκB pathways.

Comparative Efficacies of Long-Term Serial Transplantation of Syngeneic, Allogeneic, Xenogeneic, or CTLA4Ig-Overproducing Xenogeneic Adipose Tissue-Derived Mesenchymal Stem Cells on Murine Systemic Lupus Erythematosus

Allogeneic and xenogeneic transplantation are suitable alternatives for treating patients with stem cell defects and autoimmune diseases. The purpose of this study was to compare the effects of long-term serial transplantation of adipose tissue-derived mesenchymal stem cells (ASCs) from (NZB × NZW) F1 mice (syngeneic), BALB/c mice (allogeneic), or humans (xenogeneic) on systemic lupus erythematosus (SLE). The effects of transplanting human ASCs overproducing CTLA4Ig (CTLA4Ig-hASC) were also compared. Animals were divided into five experimental groups, according to the transplanted cell type. Approximately 500,000 ASCs were administered intravenously every 2 weeks from 6 to 60 weeks of age to all mice except for the control mice, which received saline. The human ASC groups (hASC and CTLA4Ig-hASC) showed a 13-week increase in average life spans and increased survival rates and decreased blood urea nitrogen, proteinuria, and glomerular IgG deposition. The allogeneic group also showed higher survival rates compared to those of the control, up to 40, 41, 42, 43, 44, 45, 52, and 53 weeks of age. Syngeneic ASC transplantation did not accelerate the mortality of the mice. The mean life span of both the syngeneic and allogeneic groups was prolonged for 6-7 weeks. Both human ASC groups displayed increased serum interleukin-10 and interleukin-4 levels, whereas both mouse ASC groups displayed significantly increased GM-CSF and interferon-γ levels in the serum. The strongest humoral immune response was induced by xenogeneic transplantation, followed by allogeneic, CTLA4Ig-xenogeneic, and syngeneic transplantations. Long-term serial transplantation of the ASCs from various sources displayed different patterns of cytokine expression and humoral responses, but all of them increased life spans in an SLE mouse model.

O-linked N-acetylglucosamine glycosylation of p65 aggravated the inflammation in both fibroblast-like synoviocytes stimulated by tumor necrosis factor-α and mice with collagen induced arthritis

Introduction

We investigated the inflammatory potential of O-linked N-acetylglucosamine glycosylation (O-GlcNAcylation) of p65 in rheumatoid arthritis (RA).

Methods

Fibroblast-like synoviocytes (FLS) and MH7A cells were treated with synthetic ThiaMet-G (200 μM), an O-GlcNAcase (OGA) inhibitor, followed by tumor necrosis factor (TNF)-α (10 μg/mL). Proliferation of synovial cells was measured by MTT assay, and the levels of mRNAs encoding pro-inflammatory molecules were quantitated by RT-PCR. The nuclear localization of O-GlcNAcylated of p65 and its DNA binding affinity and transcriptional activity were assessed. The severity assessment of arthritis and a histopathological examination were done in mice with collagen induced arthritis (CIA). ThiaMet-G (20 mg/kg) intraperitoneal injection was done every other day for 26 days. Fluorescence-activated cell sorting (FACS) analysis of T cells was performed.

Results

Hyper-O-GlcNAcylation increased the proliferation and mRNA expression of pro-inflammatory genes in synoviocytes stimulated by TNF-α. Moreover, O-GlcNAcylation of p65 enhanced its proportion of nuclear localization, DNA binding affinity and transcriptional activity. In CIA mice, ThiaMet-G significantly aggravated the severity of arthritis clinically and histologically, and it also increased CD4 + IFN-γ + T cells and CD4 + IL-17+ T cells.

Conclusions

O-GlcNAcylation of p65 increased the effects of TNF-α-mediated inflammation both in vitro (in synovial cells) and in vivo (in mice with CIA).

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0762-7) contains supplementary material, which is available to authorized users.

The potential role of advanced glycation end products (AGEs) and soluble receptors for AGEs (sRAGE) in the pathogenesis of adult-onset still's disease

Background

Accumulating evidence has demonstrated a pathogenic role of advanced glycation end products (AGEs) and receptors for AGEs (RAGE) in inflammation. Soluble RAGE (sRAGE), with the same ligands-binding capacity as full-length RAGE, acts as a “decoy” receptor. However, there has been scanty data regarding AGEs and sRAGE in adult-onset Still’s disease (AOSD). This study aimed to investigate AGEs and sRAGE levels in AOSD patients and examine their association with clinical characteristics.

Methods

Using ELISA, plasma levels of AGEs and sRAGE were determined in 52 AOSD patients, 36 systemic lupus erythematosus(SLE) patients and 16 healthy controls(HC). Their associations with activity parameters and disease courses were evaluated.

Results

Significantly higher median levels of AGEs were observed in active AOSD patients (16.75 pg/ml) and active SLE patients (14.80 pg/ml) than those in HC (9.80 pg/ml, both p < 0.001). AGEs levels were positively correlated with activity scores (r = 0.836, p < 0.001), ferritin levels (r = 0.372, p < 0.05) and CRP levels (r = 0.396, p < 0.005) in AOSD patients. Conversely, significantly lower median levels of sRAGE were observed in active AOSD patients (632.2 pg/ml) and active SLE patients (771.6 pg/ml) compared with HC (1051.7 pg/ml, both p < 0.001). Plasma sRAGE levels were negatively correlated with AOSD activity scores (r = −0.320, p < 0.05). In comparison to AOSD patients with monocyclic pattern, significantly higher AGEs levels were observed in those with polycyclic or chronic articular pattern. With treatment, AGEs levels declined while sRAGE levels increased in parallel with the decrease in disease activity.

Conclusion

The elevation of AGEs levels with concomitant decreased sRAGE levels in active AOSD patients, suggests their pathogenic role in AOSD.

Deletion of receptor for advanced glycation end products exacerbates lymphoproliferative syndrome and lupus nephritis in B6-MRL Fas lpr/j mice

The receptor for advanced glycation end products (RAGE) is a pattern recognition receptor that interacts with advanced glycation end products, but also with C3a, CpG DNA oligonucleotides, and alarmin molecules such as HMGB1 to initiate a proinflammatory reaction. Systemic lupus erythematosus is an autoimmune disorder associated with the accumulation of RAGE ligands. We generated mice invalidated for RAGE in the lupus-prone B6-MRL Fas lpr/j background to determine the role of RAGE in the pathogenesis of systemic lupus erythematosus. We compared the phenotype of these mice with that of their wild-type and B6-MRL Fas lpr/j littermates. Lymphoproliferative syndrome, production of anti-dsDNA Abs, lupus nephritis, and accumulation of CD3(+)B220(+)CD4(-)CD8(-) autoreactive T cells (in the peripheral blood and the spleen) were significantly increased in B6-MRL Fas lpr/j RAGE(-/-) mice compared with B6-MRL Fas lpr/j mice (respectively p < 0.005, p < 0.05, p < 0.001, and p < 0.001). A large proportion of autoreactive T cells from B6-MRL Fas lpr/j mice expressed RAGE at their surface. Time course studies of annexin V expression revealed that autoreactive T cells in the spleen of B6-MRL Fas lpr/j-RAGE(-/-) mice exhibited a delay in apoptosis and expressed significantly less activated caspase 3 (39.5 ± 4.3%) than T cells in B6-MRL Fas lpr/j mice (65.5 ± 5.2%) or wild-type mice (75.3 ± 2.64%) (p = 0.02). We conclude that the deletion of RAGE in B6-MRL Fas lpr/j mice promotes the accumulation of autoreactive CD3(+)B220(+)CD4(-)CD8(-) T cells, therefore exacerbating lymphoproliferative syndrome, autoimmunity, and organ injury. This suggests that RAGE rescues the apoptosis of T lymphocytes when the death receptor Fas/CD95 is dysfunctional.

Receptor for Advanced Glycation Endproducts (RAGE), Its Ligands, and Soluble RAGE: Potential Biomarkers for Diagnosis and Therapeutic Targets for Human Renal Diseases

Receptor for advanced glycation endproducts (RAGE) is a multi-ligand receptor that is able to bind several different ligands, including advanced glycation endproducts, high-mobility group protein (B)1 (HMGB1), S-100 calcium-binding protein, amyloid-β-protein, Mac-1, and phosphatidylserine. Its interaction is engaged in critical cellular processes, such as inflammation, proliferation, apoptosis, autophagy, and migration, and dysregulation of RAGE and its ligands leads to the development of numerous human diseases. In this review, we summarize the signaling pathways regulated by RAGE and its ligands identified up to date and demonstrate the effects of hyper-activation of RAGE signals on human diseases, focused mainly on renal disorders. Finally, we propose that RAGE and its ligands are the potential targets for the diagnosis, monitoring, and treatment of numerous renal diseases.

The effect of soluble RAGE on inhibition of angiotensin II-mediated atherosclerosis in apolipoprotein E deficient mice

Background

The cross talk between RAGE and angiotensin II (AngII) activation may be important in the development of atherosclerosis. Soluble RAGE (sRAGE), a truncated soluble form of the receptor, acts as a decoy and prevents the inflammatory response mediated by RAGE activation. In this study, we sought to determine the effect of sRAGE in inhibiting AngII-induced atherosclerosis in apolipoprotein E knockout mice (Apo E KO).

Methods and Results

9 week old Apo E KO mice were infused subcutaneously with AngII (1 µg/min/kg) and saline for 4 weeks using osmotic mini-pumps. The mice were divided into 4 groups 1. saline infusion and saline injection; 2. saline infusion and sRAGE injection; 3. AngII infusion and saline injection; 4. AngII infusion and sRAGE injection. Saline or 0.5 µg, 1 µg, to 2 µg/day/mouse of sRAGE were injected intraperitoneally daily for 28 days. We showed that atherosclerotic plaque areas in the AngII-infused Apo E KO mice and markers of inflammation such as RAGE, ICAM-1, VCAM-1, and MCP-1 were increased in aorta compared to that of the Apo E KO mice. However, the treatment of 0.5 µg, 1 µg, and 2 µg of sRAGE in AngII group resulted in the dose-dependent decrease in atherosclerotic plaque area. We also demonstrated that sRAGE decreased RAGE expression level as well as inflammatory cytokines and cell adhesion molecules in AngII or HMGB1 treated-rat aorta vascular smooth muscle cells.

Conclusion

The results demonstrated that partical blockade of RAGE activation by sRAGE prevent AngII -induced atherosclerosis. Therefore these results suggested that first, RAGE activation may be important in mediating AngII-induced atherogenesis, and second, AngII activation is a major pathway in the development of atherosclerosis. Taken together, results from this study may provide the basis for future anti- atherosclerotic drug development mediated through RAGE activation.